Apparatus is known which prevents current spikes in the motor circuit during the startup of the motor. In particular such current spikes are to be avoided, since in household appliances they may cause the blowing of fuses or the opening of circuit breakers.
In other known equipment, the no load speed of an electric motor in a processing machine is decreased by means of a current limiting circuit in order that the motor noise be decreased. This type of current limiting circuit includes a controllable semiconductor whose cut-in phase angle is varied as a function of motor current. This circuit requires a relatively large amount of electronic circuit elements, in particular because the controllable semiconductor and its heat sink must be designed for the maximum allowable motor current. This requires relatively expensive controllable semiconductor elements and also relatively expensive and large heat sinks. Further, the known circuits are subject to thermal overload even when properly designed. This thermal overload can lead to a destruction of the semiconductor elements. This is particularly the case for electric tools such as saws where the ventilating slits in the motor housing tend to become clogged and thus have a decreased cooling effect.